If you've ever wanted to go ghost hunting, SpecTrek lets you chase spectres using your smartphone's GPS. The augmented reality game shows you "ghosts" on a map of your area and gives you a time limit to find and capture them.

It may be kind of silly, but hey, it's probably the most fun you'll ever have using a smartphone GPS.

3. Entity Sensor Pro app for Android

If virtual ghosts don't cut it for you, the Entity Sensor Pro app for Android claims to let you detect "real" ghosts using a supposed EMF sensor in your smartphone to check for "paranormal" readings.

It's essentially like playing Ghost Busters with a mobile device. Whether or not you actually believe in ghosts, the app has a pretty high rating among users.

And even if you think it's useless as a ghost detector, you can always use it with friends as a gullibility detector.

4. Ouija Board app for Android

Like so many classics, the Ouija Board has been revamped for modern mobile devices.

Use your smartphone to try making contact with the spirit world, or simply relive the fun of middle school with this Android app. In any case, it gives new meaning to "the ghost in the machine."

You can add a little eerie appeal to party pics with the Ghost Camera Pro smartphone app for Android.

The app lets you choose from a bunch of different types of ghosts and spirits (not just the cute kind pictured above) and insert them into pictures on your device. You can also edit the size, color and opacity of your ghosts.

We consider this more of a humor app, especially if some of some of your subjects have been going at the punch bowl hard.